Rotational body driving apparatus and an image forming apparatus in use therewith

Abstract

An image forming apparatus having a rotational body. The apparatus includes: the rotating body such as a photoreceptor drum; a driver for driving the rotating body; the first member, provided in a driving transmission path of the driving force, for transmitting the driving force from the driving source to the rotating body, and for elastically deforming itself so as to control a natural frequency value of a driving system including the rotating body and driving source; and the second member, provided in the driving transmission path of the driving force, for controlling damping characteristics of the driving system.

What is claimed is: 
     
       1. An image forming apparatus, comprising: a rotating body;   a driving source for driving said rotating body;   a first member, provided in a driving transmission path of a driving force, for transmitting said driving force from said driving source to said rotating body, and for elastically deforming itself so as to control a natural frequency value of a driving system including said rotating body and driving source; and   a second member, provided in said driving transmission path of said driving force, for controlling damping characteristics of said driving system.   
     
     
       2. The image forming apparatus of claim 1, wherein said rotating body comprises a photoreceptor drum. 
     
     
       3. The image forming apparatus of claim 1, wherein said rotating body comprises a driving roller for driving a photoreceptor belt. 
     
     
       4. The image forming apparatus of claim 1, wherein damping characteristics of said driving system by effect of said second member is larger than that of said first member. 
     
     
       5. The image forming apparatus of claim 1, wherein said first member is provided between said driving source and said rotating body and said second member increases damping characteristics caused by said first member. 
     
     
       6. The image forming apparatus of claim 1, wherein said second member controls a damping coefficient of said driving system. 
     
     
       7. The image forming apparatus of claim 11 wherein said second member controls damping characteristics of said driving system so as to decrease vibration of said driving system. 
     
     
       8. The image forming apparatus of claim 1, wherein said second member decreases vibration of said first member as a part of said driving system. 
     
     
       9. The image forming apparatus of claim 8, wherein said second member is an elastic material whose JIS rubber hardness is in a range from 20 degrees to 100 degrees. 
     
     
       10. The image forming apparatus of claim 1, wherein said second member is attached to said first member. 
     
     
       11. The image forming apparatus of claim 10, wherein said second member is provided inside said first member. 
     
     
       12. The image forming apparatus of claim 11, wherein said second member is compressed at a predetermined pressure inside said first member. 
     
     
       13. The image forming apparatus of claim 10, wherein said second member has a surface contact with said first member. 
     
     
       14. The image forming apparatus of claim 1, further comprising: a driving force transmitting member, being rotated by said driving source, for transmitting said driving force to said rotating body wherein a rigid protrusion is provided to said driving force transmitting member; and   wherein said first member is fixed to a side surface of said rotating body and said first member is coupled with said protrusion of said driving force transmitting member.   
     
     
       15. The image forming apparatus of claim 14, wherein said driving force transmitting member comprises a driving gear. 
     
     
       16. The image forming apparatus of claim 14, wherein said first member includes at least a beam-shaped portion, said first member is coupled with said protrusion through said beam-shaped portion, and said second member is in contact with said first member on the side other than that where said first member is coupled with said protrusion. 
     
     
       17. The image forming apparatus of claim 14, wherein said first member includes at least a beam-shaped portion, said first member is coupled with said protrusion through said beam-shaped portion, and said second member is in contact with said first member on a surface of the side that said first member is coupled with said protrusion. 
     
     
       18. The image forming apparatus of claim 14, wherein said first member includes at least a beam-shaped portion, said first member is coupled with said protrusion through said beam-shaped portion, and said second member is in contact with said first member on the same side that said first member is coupled with said protrusion. 
     
     
       19. The image forming apparatus of claim 1, further comprising: a driving force transmitting member, being rotated by said driving source, for transmitting said driving force to said rotating body wherein said first member is fixed to said driving force transmitting member; and   wherein a rigid protrusion is formed to a side surface of said rotating body and said protrusion is coupled with said first member of said driving force transmitting member.   
     
     
       20. The image forming apparatus of claim 19, wherein said driving force transmitting member comprises a driving gear. 
     
     
       21. The image forming apparatus of claim 1, wherein said first member is mainly composed of an elastic material selected from POM, ABS resins, SUS alloys, SECC, and aluminum alloys. 
     
     
       22. The image forming apparatus of claim 1, wherein said second member is an elastic material whose loss factor tan δ is not less than 0.3. 
     
     
       23. The image forming apparatus of claim 1, wherein said second member is composed of a viscoelastic material selected from EPDM, silicone gel, oil-impregnated porous rubber, butyl rubber, thermoplastic elastomer, and thermoplastic resin. 
     
     
       24. The image forming apparatus of claim 1, wherein said second member is in contact with said first member wherein said second member is compressed in advance with compressibility between 1% and 15%.